This invention relates to countermeasure techniques for protecting aircraft from enemy attack and, more particularly, to a means of protecting an aircraft by deceiving an enemy into tracking a decoy target.
Various systems are being employed and have been proposed for protecting aircraft from enemy attack including the use of jamming equipment on the aircraft. When the threat is from tracking radars or missile seekers employing monopulse or pseudo-monopulse angular error sensing mechanisms the difficulty of countermeasures increases since few electronic countermeasures techniques exist. One of the well known techniques is that of producing false targets at a physical distance from the aircraft under attack.
One means of producing such false targets is to employ expendable active decoys. These devices are ejected at an angle from an aircraft when under attack and usually contain active electronic components (which usually include a repeater or transponder). The repeater or transponder duplicates the incoming signal from the enemy radar but provides misinformation as to the doppler and bearing of the aircraft under attack due to the different velocity of the ejected decoy and the angular difference between the ejected decoy and the “true” target.
While such expendable active decoys have proven successful, they are limited in power level, bandwidth, cost and size. To be useful their size must be sufficiently small such that a fair number of them can be carried aboard an aircraft. Therefore, the amount of electronics incorporated therein must be reasonably limited occasioning a limitation in bandwidth and power level which they output. Notwithstanding the size limitations which have been imposed, the expendable active decoys are still relatively large and costly and the number which can be carried aboard an aircraft during a mission is limited.
Accordingly, it is an object of this invention to provide improved electronic countermeasures.
It is another object of this invention to provide an improved expendable decoy.